The invention relates to a method for the pretreatment of polymer surfaces of components to be painted in which at least one polymer surface of at least one component is cleaned inside a pretreatment cell and subsequently treated with an oxidizing flame.
Components made of polymer substances, for example, plastic bumpers for the automotive industry, are commonly painted in a three-step painting process; as a rule, an undercoat or primer is applied, then a colored base coat is applied, and finally a clear lacquer surface is applied. Omitting the undercoat primer and applying the base coat directly to the plastic substrate is also known. An additional known solution involves single-coat painting or dual-coat painting using solvents or water-based paints
As a rule, before painting the surfaces of such components, the components are pretreated, with a typical pretreatment including cleaning the surface of the component and, after cleaning the surface, a treatment of the surface with an oxidizing flame, in particular for improving the adhesive properties. Here, the surface cleaning is conducted by means of an aqueous, multi-zone washing system or using carbon dioxide snow (CO2 snow) or carbon dioxide pellets (CO2 pellets). The two process steps, i.e., cleaning and flame treatment, occur in cells or parts of the system that are separate, enclosed, and separately ventilated.
This known distribution of the two process steps into two such separate cells requires a large amount of space, which is associated with a high energy use. Moreover, this known division of the two process steps is associated with long throughput times. Finally, after the surface has been cleaned, the component must be transferred out of the cell in which it was cleaned and into the cell provided for flame treatment. In spite of all preventative measures, undesired impurities often occur during transfer of the already-cleaned component surface due to outside influences, which ultimately have a detrimental effect on the quality of the paint job.
Therefore, overall, the currently known methods for the pretreatment of polymer surfaces to be painted are very cost-intensive and laborious. Moreover, these methods are quite susceptible to contaminations that are detrimental to quality.
What is needed therefore is a method for the pretreatment of polymer surfaces of components to be painted by means of which a cost-effective and practical pretreatment of polymer surfaces to be painted is possible as compared to known solutions, and by means of which the quality of the paint job may be improved.